This invention relates to trilobal cross-section fibers or filaments, for use as carpet yarn, for example, and more particularly to a spinnerette for their manufacture. The invention further relates to bi-component fibers and their manufacture.
Many current upholstery and carpet products are made of filaments or fibers spun from polymers. Typically, a polymer stream is passed through capillaries, or orifices, in a spinnerette to achieve a specific profile or cross-section. The profiles of these spun synthetic fibers are typically designed to have high stability and bending strength, and to part a high gloss and bulk to the finished product. Most current spun polymer filaments are composed of conventional synthetic polymers, such as nylon, polyester, or polyolefin polymers. In many instances, nylon 6-6 and its copolymers are used to produce yarn.
It has been found that bi-component filaments permit the manufacture of a carpet filament that combines the beneficial properties of two different polymers. In addition, it has also been found that filaments manufactured in a sheath/core relationship frequently have improved flexural rigidity and bending resistance. In the past, bi-component trilobal filaments have been produced by combining polymer streams in a manner similar to that disclosed in the patent to Matsui, U.S. Pat. No. 3,568,249. As disclosed in that reference, a first polymer stream passes through a trilobal shaped capillary and subsequently combines with a second polymer stream in which the first and second polymer streams pass jointly through a second trilobal shaped spinnerette capillary. Prior methods such as disclosed in the Matsui patent rely heavily upon the viscosity of the inner polymer stream to maintain a proper cross-sectional relationship when combining with the outer polymer material passing through the last spinnerette capillary. Moreover, procedures of this type require multiple spinnerettes. Control of temperature and pressure of the two polymer streams is also critical in these prior procedures.
The patent to Samuelson, U.S. Pat. No. 4,743,189, discloses a bi-component filament which includes a trilobal core within a circular sheath. The core in this device filament is free (i.e., not fused) from the inner surface of the circular outer sheath. While the Samuelson reference discloses a trilobal core, the overall profile of the filament is circular, thereby losing the beneficial effects of a trilobal or triangular profile shape.
On the other hand, the patent to Peterson et al., U.S. Pat. No. 4,648,830, discloses a spinnerette for producing a hollow trilobal cross-section filament. This reference, however, does not disclose a bi-component filament or spinnerette for producing such a filament.
There remains a need for a spinnerette for producing a bi-component filament having a trilobal or triangular profile in order to obtain the benefits associated with these profile shapes and bi-component material properties.